1. Field of the Invention
The present invention relates to a rechargeable battery and a method for manufacturing the same. More specifically, the present invention relates to a rechargeable battery in which a case is connected to at least one lead tab in a manner that reduces the introduction of residue or spatter within the case, and a method for manufacturing the rechargeable battery.
2. Description of the Related Art
In a typical lithium-ion rechargeable battery, an electrode assembly and an electrolyte are housed and sealed in a case. Lithium-ion rechargeable batteries are divided into two types, i.e. can-type and pouch-type lithium-ion rechargeable batteries, by the kind of case materials employed.
For example, a can-type lithium-ion rechargeable battery comprises an electrode assembly and a metal case electrically connected to a cathode or an anode of the electrode assembly.
The electrode assembly is electrically connected to the case by a lead tab. The connection between the case and the lead tab is achieved by any suitable process, mostly by resistance welding.
The resistance welding process, however, is problematic because weld spatter is produced which can cause shorting of the electrode assembly.
When it is intended to improve the conductivity between the electrode assembly and the case, two or more partially overlapping lead tabs are often used. In that case, resistance welding is often performed to connect the individual lead tabs to the case, which lengthens the manufacturing time and makes the manufacturing process more complex.
Further, low resistance between the case and the lead tabs can lead to the formation of a defective welded joint during resistance welding. Often, the materials forming the leads have low resistance which reduces the heat generated thereby producing less effective welds.